Treatment of organic materials



United States Patent Q James D. Wolfe, Edmond, Okla, assignor to Kerr-McGee Oil Industries, Inc, a corporation of Delaware Application September 4, 1956 Serial No. 607,557

15 Claims. (Cl. 208-252) No Drawing.

The present invention relates to the processing of organic materials and more particularly to an improved process for reducing the trace metal content of such materials.

The process of the invention will be described and illustrated herein with particular reference to petroleum crudes and fractions derived therefrom, such as asphalt, asphaltic oils, lubricating oils, and petroleum mixtures useful as catalytic cracking stocks. However, it will be appreciated by those skilled in the art that the process of the invention is also applicable to other types of relatively high molecular Weight organic materials possessing somewhat similar properties when treated by the process and under the conditions taught herein.

Petroleum crudes and the above mentioned petroleum fractions generally contain trace metals such as nickel and vanadium which are believed to be present as organic complexes. The nature of these complexes is not fully understood, but the metals are thought to be largely held in oil-soluble organic complexes such asthe metal porphyrin complexes reported in the literature. Whatever their nature, the presence of tracetmetals is usually highly undesirable in petroleumand itsvarious fractions and severely restricts their use for many purposes, such as for catalytic cracking stocks or fuels for internal combustion engines.

It is an object of the present invention to provide a novel process for reducing the trace metal content of relatively high molecular weight organic materials.

It is a further object of the present invention to provide a novel process for reducing the trace metal content of high molecular weight hydrocarbons and oils of petroleum origin.

It is still a further object of the present invention to provide a novel process for reducing the trace metal content of the foregoing materials wherein such materials are treated with a suitable fiuoro-phosphoric acid.

Still other objects of the present invention and the attendant advantages will be apparent to those skilled in the art by reference to the following detailed description and the specific examples.

We have discovered that a wide variety of high molecular weight organic materials maybe substantially reduced in nickel, vanadium or other trace metal content and without appreciable loss to sludge by treatment with a suitable fiuoro-phosphoric acid. The process of the invention is particularly useful in treating petroleum crudes and heavier fractions derived therefrom such as asphalt, asphaltic oils, lubricating oils, and petroleum mixtures useful as catalytic cracking stocks. Such materials may be referred to in the specification and claims as high molecular weight hydrocarbons and oils.

It is generally preferred that the high molecular weight hydrocarbons and oils, particularly when the'material is somewhat viscous in nature, be first dissolved in an excess of inert solvent before treatment with the fluorophosphoric acid treating agent. Examples of suitable inert solvents are those solvents substantially inert under the, conditions taught herein such as .pentane, mineral spirits, or petroleum distillates in general. The preferred solvent is a naphtha distillate fraction having a distillation range between 150 and 270 F. The quantity of solvent employed may vary over wide ranges but preferably should be sufiicient to provide a solution having a relatively low viscosity. For example, in treating asphaltic oil the preferred solvent to oil ratio is about ten to one by volume.

Examples of suitable fluoro-phosphoric acid treating agents found particularly useful in practicing the present invention are monofiuorophosphoric acid, difluorophosphoric acid, hexa-fluorophosphoric acid, and mixtures thereof. The above mentioned fluorophosphoric acids are presently preferred for a number of reasons, one reason being their more selective action for trace metals results in higher yield of treated product and lower trace metal content. Still another reason for preferring these fluorophosphoric acids is that they apparently reduce the trace metal content by solvent action and thus do not cause a separation between paraffinic and aromatic hydrocarbons in order to reduce the trace metal content.

The commercial mixture of the above fluorophosphoric acids, i.e., the mixture as usually produced in commercial practice and before separation into the individual fluorophosphoric acids, has been found to be satisfactory and thus is preferred for economic reasons.

In accordance with the present invention, a quantity of treating agent sufficient to give the desired reduction in trace metalcontent may be mixed directly with the high molecular weight hydrocarbons or oils tobe treated. However, it is generally desirable tOfilfSt dissolve such materials in about one to ten'volumesof inert solvent and then add the treating agent. The ratio of treating agent to material to be treated may vary over a considerable range, e.g., about 1005:1"to 1:1 Usually a ratio between about .01:1 to .0521 issufiicient but-a ratio of .0421 or higher may? be preferred. The resulting mixture is then agitated for several hours and preferably at elevated temperature. A'period of treatment of about 1 to 4hours at a'ternperature between about F. to reflux temperature of'the mixture is usually sufiicient to reduce the trace metal content to an acceptable level. On standing, a sludge layer separates from the treated mixture. The sludge layer may be separated from the mixture by decanting, or other suitable method and solvent, if present, is flashed off. Any excess treating agent may be removed from the treated and separated mixture by stripping with water. The treating loss under preferred conditions taught herein, calculated as sludge, is usually less than 5% by weight of the untreated material.

The process of the present invention may be further illustrated by the following specific examples:

EXAMPLE I An asphaltic oil was prepared from asphalt by the conventional propane treatment well'known in the art. The particular asphaltic oil used in this and the following example analyzed 29 ppm. vanadium and 30 ppm. nickel before treatment.

A sample of the above asphaltic oil was mixed directly with 5% by weight of monofluorophosphoric acid and the resultant mixture agitated for 1 hour at room temperature. Upon standing, a sludge layer formed which was drawn off leaving the oil layer. The oil layer was stripped free of monofluorophosphoric acid by washing with water andthen analyzed for vanadiumand nickel. The analysis indicated a reduction in vanadium and nickel content to about 10 ppm. in each instance, but treating losses were in excess of 30% due tothe excessive amount of sludge formed by this treatment.

3 EXAMPLE n A sample of asphaltic oil identical with that of Example I was first dissolved in volumes of suitable inert solvent to one volume of oil and then treated with various treating agents. The treating agent to oil ratio was varied between 0.005 :1 and 1:1, and the period of treatment between 1 and 4 hours at temperatures between 70 F. and reflux temperature of the particular solvent. Treatment was at atmospheric pressure. After the treatment was completed, the solution was allowed to stand for a period of time sufiicient to allow separation of a sludge layer. The sludge layer was then drawn off, the oil layer freed of solvent and stripped free of treating agent by washing with water. The treated asphaltic oil was then analyzed for vanadium and nickel and the results recorded. The treating loss was based on the weight of untreated oil and calculated as the percentage by weight of sludge separated from the oil layer.

The following table illustrates results obtained by varying the treating conditions within the foregoing limits.

an elevated temperature above 70 F. and up to the reflux temperature over a period of time suflicient to reduce the trace metal content, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

2. A process for reducing the, trace metal content of high molecular weight hydrocarbons and oils comprising the steps of contacting at least one of such materials containing a trace metal with a treating agent consisting essentially of at least one fiuorophosphoric acid selected from the class consisting of monofiuorophosphoric, difluorophosphoric acid and hexafluorophosphoric acid the material being contacted with the treating agent at an elevated temperature above 70 F. and up to the reflux temperature over a period of time suflicient to reduce the trace metal content, the ratio by weight of treating agent to the material to be treated being from 0.005z1 to 1:1, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

3. The process of claim 2 wherein the ratio by weight Table 1 Trace Metal Gon- Treatment Condition tent of Treated Treating Treat. Product Run Solvent Treating Agent to Loss, No. Agent 011 Ratio Percent (by weight) Agita Temp., Pres- Venadi- Nickel, tion, F. sure, um, p.p.m. Hrs. p.s.i. p.p.m.

Untreated As- 29 phaltic Oil 1 Pentane HaPOaF 0. 14:1 1 10-90.... 14. 7 11 16 23 d 0. 28:1 1 7090...- 14. 7 18 7 13 0. 1:1 4 reflux- 14. 7 18 10 12 1:1 3 14. 7 22 8. 2 5. 9 0. 04:1 1 14. 7 10 15 22 0. 12:1 1 14. 7 11 11 18 0. 24:1 1 14. 7 9 16 0. 16:1 3 14. 7 6 13 17 0. 4:1 1 14. 7 9 13 19 HPO|F: 0. 12:1 1 l4. 7 15 4. 2 11 HPO;F 0. 26:1 1 14. 7 18 4. 8 5.9 HPOQF1 0. 005:1 1 14. 7 2 22 21 HPOgFg--. 0. 04:1 1 14. 7 4 17 28 HPOQF1 (1. 04:1 4 14. 7 4 3. 3 6. 8 HPOgFg 1:1 1 14. 7 15 1. 5 4. 5 HPOgFz... 0.1:1 3 14. 7 8 10 14 It is apparent from the above table that the process of the present invention is highly effective for removing trace metals. However, the process is largely inefl'ective for the removal of sulfur. For example, a sulfur analysis on untreated asphaltic oil used in the foregoing examples indicated the sulfur content to be about 1.78%. A sulfur analysis on treated asphaltic oil of run No. 14 indicated a sulfur content of 1.76%, a reduction of only .O2%.

Run N0. 14 appearing in the foregoing table illustrates the presently preferred procedure. This experiment utilizes 10 volumes of isooctane as a solvent, difluorophosphoric acid as the treating agent,.a treating agent to oil ratio of 0.04:1 by weight, and a treating period of four hours at reflux temperature. Under such conditions the treatment loss is reduced to 4%, While the vanadium and nickel content of the asphaltic oil is reduced to 3.3 ppm. and 6.8 p.p.rn., respectively.

The foregoing detailed description and the specific examples are for the purpose of illustrating the present invention only, and are not to be taken as limiting to the scope or spirit of the appended claims.

What is claimed is:

1. A process for reducing the trace metal content of high molecular weight hydrocarbons and oils comprising the steps of contacting at least one of such materials containing a trace metal with a treating agent consisting essentially of at least one fiuorophosphoric acid selected from the class consisting of monofluorophosphoric acid, difluorophosphoric acid and hexafluorophosphoric acid, the material being contacted with the treating agent at of treating agent to the material to be treated is at least 0.04:1.

4. A process for reducing the trace metal content of high molecular weight hydrocarbons and oils comprising the steps of contacting at least one of such materials containing a trace metal with a treating agent consisting essentially of at least one fluorophosphoric acid selected from the class consisting of monofluorophosphoric acid, difluorophosphoric acid and hexafiuorophosphoric acid, the material being contacted with the treating agent at an elevated temperature above 70 F. and up to the reflux temperature over a period of about 1-4 hours, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

5. A process for reducingthe trace metal content of high molecular weight hydrocarbons and oils comprising the steps of contacting at least one of such materials containing a trace metal with a treating agent consisting essentially of at least one fluorophosphoric acid selected from the class consisting of monofluorophosphoric acid, difluorophosphoric acid and hexafluorophosphoric acid, the material being contacted with the treating agent at an elevated temperature above 70 F. and up to the reflux temperature over a period of about 1-4 hours, the ratio by weight of treating agent to the material to be treated being from 0.005 :1 to 1:1, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

6. The process of claim 5 wherein the ratio by weight of treating agent to the material to be treated is at least 0.04:1.

7. The process of claim 6 wherein the treating agent is monofiuorophosphoric acid.

8. The process of claim 6 wherein the treating agent is difluorophosphoric acid.

9. The process of claim 6 wherein the treating agent is hexafluorophosphoric acid.

10. A process for reducing the trace metal content of high molecular weight hydrocarbons and oils comprising the steps of dissolving at least one of such substances containing a trace metal in inert solvent, contacting the resultant solution with a treating agent consisting essentially of at least one fluorophosphoric acid selected from the class consisting of monofluorophosphoric acid, difluorophosphoric acid and hexafluorophosphoric acid, the solution being contacted with the treating agent at an elevated temperature above 70 F. and up to the reflux temperature over a period of time sufiicient to reduce the trace metal content, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

11. A process for reducing the trace metal content of high molecular weight hydrocarbons and oils comprising the steps of dissolving at least one of such materials containing a trace metal in inert solvent, contacting the resultant solution with a treating agent consisting essentially of at least one fiuorophosphoric acid selected from the class consisting of monofiuorophosphoric acid, difluorophosphoric acid and hexafluorophosphoric acid, the solution being contacted with the treating agent at an elevated temperature above 70 F. and up to the reflux temperature over a period of time sufficient to reduce the trace metal content, the ratio by weight of treating agent to the material to be treated being from 0.005 :1 to 1:1, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

12. The process of claim 11 wherein the ratio by weight of treating agent to the material to be treated is at least 0.04:1.

13. A process for reducing the trace metal content of high molecular weight hydrocarbons and oils comprising the steps of dissolving at least one of such materials containing a trace metal in inert solvent, contacting the resultant solution with a treating agent consisting essentially of at least one fluorophosphoric acid selected from the class consisting of monofluorophosphoric acid, difluorophosphoric acid and hexafluorophosphoric acid, the solution being contacted with the treating agent at an elevated temperature above F. and up to the reflux temperature over a period of about l-4 hours, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

14. A process for reducing the trace metal content of high molecular weight hydrocarbons and oils comprising the steps of dissolving at least one of such materials containing a trace metal in inert solvent, contacting the resultant solution with a treating agent consisting essentially of at least one fluorophosphoric acid selected from the class consisting of monofluorophosphoric acid, difluorophosphoric acid and hexafiuorophosphoric acid, the solution being contacted with the treating agent at an elevated temperature above 70 F. and up to the reflux temperature over a period of about 1-4 hours, the ratio by weight of treating agent to the material being treated being from 0.005:l to 1:1, forming a sludge layer and a layer of treated material, and separating the layers thus formed.

15. The process of claim 14 wherein the ratio by weight of treating agent to the material to be treated is at least 0.04: 1.

References Cited in the file of this patent UNITED STATES PATENTS 2,611,735 Coons Sept. 23, 1952 2,729,593 Garwood Jan. 3, 1956 2,762,751 Slaughter et al. Sept. 11, 1956 2,789,116 Van Eck Apr. 16, 1957 FOREIGN PATENTS 1,065,848 France Ian. 13, 1954 

1. A PROCESS FOR REDUCING THE TRACE METAL CONTENT OF HIGH MOLECULAR WEIGHT HYDROCARBON AND OILS COMPRISING THE STEPS OF CONTACTING AT LEAST ONE OF SUCH MATERIALS CONTAINING A TRACE METAL WITH A TREATING AGENT CONSISTING ESSENTIALLY OF AT LEAST ONE FLUOROPHOSPHORIC ACID SELECTED FROM THE CLASS CONSISTING OF MONOFLUOROPHOSPHORIC ACID, DIFLUOROPHOSPHORIC ACID AND HEXAFLUOROPHOSPHORIC ACID, THE MATERIAL BEING CONTACTED WITH THE TREATING AGENT AT AN ELEVATED TEMPERATURE ABOVE 70*F. AND UP TO THE REFLUX TEMPERATURE OVER A PERIOD OF TIME SUFFICIENT TO REDUCE THE TRACE METAL CONTENT, FORMING A SLUDGE LAYER AND A LAYER OF TREATED MATERIAL, AND SEPARATING THE LAYERS THUS FORMED. 